Boosting the Zn2+ storage capacity of MoO3 nanoribbons by modulating the electrons spin states of Mo via Ni doping.

Aqueous zinc-ion batteries (AZIBs) have received considerable potential for their affordability and high reliability. Among potential cathodes, α-MoO3 stands out due to its layered structure aligned with the (010) plane, offering extensive ionic insertion channels for enhanced charge storage. However, its limited electrochemical activity and poor Zn2+ transport kinetics present significant challenges for its deployment in energy storage devices. To overcome these limitations, we introduce a new strategy by doping α-MoO3 with Ni (Ni-MoO3), tuning the electron spin states of Mo. Thus modification can activate the reactivity of Ni-MoO3 towards Zn2+ storage and weaken the interaction between Ni-MoO3 and intercalated Zn2+, thereby accelerating the Zn2+ transport and storage. Consequently, the electrochemical properties of Ni-MoO3 significantly surpass those of pure MoO3, demonstrating a specific capacity of 258 mAh g-1 at 1 A g-1 and outstanding rate performance (120 mAh g-1 at 10 A g-1). After 1000 cycles at 8 A g-1, it retains 76 % of the initial capacity, with an energy density of 154.4 Wh kg-1 and a power density of 11.2 kW kg-1. This work proves that the modulation of electron spin states in cathode materials via metal ion doping can effectively boost their capacity and cycling durability.

Unraveling the Mechanism of Cooperative Redox Chemistry in High-Efficient Zn2+ Storage of Vanadium Oxide Cathode.

The inferior capacity and cyclic durability of V2 O5 caused by inadequate active sites and sluggish kinetics are the main problems to encumber the widespread industrial applications of vanadium-zinc batteries (VZBs). Herein, a cooperative redox chemistry (CRC) as "electron carrier" is proposed to facilitate the electron-transfer by capturing/providing electrons for the redox of V2 O5 . The increased oxygen vacancies in V2 O5 provoked in situ by CRC offers numerous Zn2+ storage sites and ion-diffusion paths and reduces the electrostatic interactions between vanadium-based cathode and intercalated Zn2+ , which enhance Zn2+ storage capability and structural stability. The feasibility of this strategy is fully verified by some CRCs. Noticeably, VZB with [Fe(CN)6 ]3- /[Fe(CN)6 ]4- as CRC displays conspicuous specific capacity (433.3 mAh g-1 ), ≈100% coulombic efficiency and superb cyclability (≈3500 cycles without capacity attenuation). Also, the mechanism and selection criteria of CRC are specifically unraveled in this work, which provides insightful perspectives for the development of high-efficiency energy-storage devices.

Weak Solvation Effect Induced Optimal Interfacial Chemistry Enables Highly Durable Zn Anodes for Aqueous Zn-Ion Batteries.

Aqueous zinc-ion batteries (AZIBs) are emerging as one of the most reliable energy storage technologies for scale-up applications, but still suffer from the instability of Zn anode, which is mainly caused by the undesirable dendrite growth and side reactions. To tackle these issues, we formulate a new aqueous electrolyte with weak solvation effect by introducing low-dielectric-constant acetone to achieve H2 O-poor solvation structure of Zn2+ . Experimental and theoretical calculation studies concurrently reveal that such solvation structure can: i) relieve the solvated H2 O related side reactions, ii) suppress the dendrite growth by boosting the desolvation kinetics of Zn2+ and iii) in situ form solid electrolyte interface (SEI) to synergistically inhibit the side reaction and dendrite growth. The synergy of these three factors prolongs the cycling life of Cu/Zn asymmetric cell from 30 h to more than 800 h at 1 mA cm-2 /1 mAh cm-2 , and can work at more harsh condition of 5 mA cm-2 /5 mAh cm-2 . More encouragingly, Zn/V2 O5 ⋅ nH2 O full cell also shows enhanced cycling stability of 95.9 % capacity retention after 1000 cycles, much better than that with baseline electrolyte (failing at ≈700th  cycle).

Structural and surface engineering promotes Zn-ion energy storage capability of commercial carbon cloth.

Aqueous Zn-ion hybrid supercapacitors (AZHSCs) combining the advantages of high-energy batteries and high-power supercapacitors see a bright future, but they still suffer from the poor capacity of carbonic cathodes. Herein, a functionalized porous carbon cloth (denoted as FPCC) electrode is demonstrated based on commercial carbon cloth (denoted as CC) tuning by structural and surface engineering. The constructed exfoliated porous carbon layer and the negatively charged functionalized interface not only increase the electrical double layer capacitance but also favor the chemical adsorption of Zn2+ to obtain additional pseudocapacitance. Consequently, the FPCC electrode delivers a high capacity of 0.16 mAh cm-2 at 4 mA cm-2, which is 923.8 times higher than CC, and a long cycle life (85.0% capacity retention after 30 000 cycles). More importantly, the Zn//FPCC AZHSC possesses an impressive energy density (3.3 mWh cm-3) and power density (240 mW cm-3), superior to many advanced batteries and supercapacitors. The quasi-solid-state device is also assembled as a demo. This modification strategy may provide new opportunities for high-performance AZHSCs.

Facile fabrication of hierarchical ultrathin Rh-based nanosheets for efficient hydrogen evolution.

Rational design of efficient and stable electrocatalysts for the hydrogen evolution reaction (HER) has attracted wide attention. Noble metal-based electrocatalysts with ultrathin structures and highly exposed active surfaces are essential to boost the HER performance, while the simple synthetic strategies remain challenging. Herein, we reported a facile urea-mediated method to synthesize hierarchical ultrathin Rh nanosheets (Rh NSs) without using toxic reducing agents and structure directing agents in the reaction. The hierarchical ultrathin nanosheet structure and grain boundary atoms endow Rh NSs with excellent HER activities, which only requires a lower overpotential of 39 mV in 0.5 M H2SO4 compared to the 80 mV of Rh nanoparticles (Rh NPs). Extending the synthesis method to alloys, hierarchical ultrathin RhNi nanosheets (RhNi NSs) can be also obtained. Benefiting from the optimization of electronic structure and abundant active surfaces, RhNi NSs only require an overpotential of 27 mV. This work provides a simple and promising method to construct ultrathin nanosheet electrocatalysts for highly active electrocatalytic performance.

Boosting the capacity and stability of a MoO3 cathode via valence regulation and polypyrrole coating for a rechargeable Zn ion battery.

Molybdenum trioxide (MoO3) is emerging as a hugely competitive cathode material for aqueous zinc ion batteries (ZIBs) for its high theoretical capacity and electrochemical activity. Nevertheless, owing to its undesirable electronic transport capability and poor structural stability, the practical capacity and cycling performance of MoO3 are yet unsatisfactory, which greatly blocks its commercial use. In this work, we report an effective approach to first synthesise nanosized MoO3-x materials to provide more active specific surface areas, while improving the capacity and cycle life of MoO3 by introducing low valence Mo and coated polypyrrole (PPy). MoO3 nanoparticles with low-valence-state Mo and PPy coating (denoted as MoO3-x@PPy) are synthesized via a solvothermal method and subsequent electrodeposition process. The as-prepared MoO3-x@PPy cathode delivers a high reversible capacity of 212.4 mA h g-1 at 1 A g-1 with good cycling life (more than 75% capacity retention after 500 cycles). In contrast, the original commercial MoO3 sample only obtains a capacity of 99.3 mA h g-1 at 1 A g-1, and a cycling stability of 10% capacity retention over 500 cycles. Additionally, the fabricated Zn//MoO3-x@PPy battery obtains a maximum energy density of 233.6 W h kg-1 and a power density of 11.2 kW kg-1. Our results provide an efficient and practical approach to enhance commercial MoO3 materials as high-performance cathodes for AZIBs.

Sodium Ion Pre-Intercalation of δ-MnO2 Nanosheets for High Energy Density Aqueous Zinc-Ion Batteries.

With the merits of low cost, environmental friendliness and rich resources, manganese dioxide is considered to be a promising cathode material for aqueous zinc-ion batteries (AZIBs). However, its low ion diffusion and structural instability greatly limit its practical application. Hence, we developed an ion pre-intercalation strategy based on a simple water bath method to grow in situ δ-MnO2 nanosheets on flexible carbon cloth substrate (MnO2), while pre-intercalated Na+ in the interlayer of δ-MnO2 nanosheets (Na-MnO2), which effectively enlarges the layer spacing and enhances the conductivity of Na-MnO2. The prepared Na-MnO2//Zn battery obtained a fairly high capacity of 251 mAh g-1 at a current density of 2 A g-1, a satisfactory cycle life (62.5% of its initial capacity after 500 cycles) and favorable rate capability (96 mAh g-1 at 8 A g-1). Furthermore, this study revealed that the pre-intercalation engineering of alkaline cations is an effective method to boost the properties of δ-MnO2 zinc storage and provides new insights into the construction of high energy density flexible electrodes.

One-Pot Synthesis of NiSe2 with Layered Structure for Nickel-Zinc Battery.

Transition metal organic framework materials and their selenides are considered to be one of the most promising cathode materials for nickel-zinc (denoted as Ni-Zn) batteries due to their low cost, environmental friendliness, and controllable microstructure. Yet, their low capacity and poor cycling performance severely restricts their further development. Herein, we developed a simple one-pot hydrothermal process to directly synthesize NiSe2 (denotes as NiSe2-X based on the molar amount of SeO2 added) stacked layered sheets. Benefiting from the peculiar architectures, the fabricated NiSe2-1//Zn battery based on NiSe2 and the Zn plate exhibits a high specific capacity of 231.6 mAh g-1 at 1 A g-1, and excellent rate performance (162.8 mAh g-1 at 10 A g-1). In addition, the NiSe2//Zn battery also presents a satisfactory cycle life at the high current density of 8 A g-1 (almost no decay compared to the initial specific capacity after 1000 cycles). Additionally, the battery device also exhibits a satisfactory energy density of 343.2 Wh kg-1 and a peak power density of 11.7 kW kg-1. This work provides a simple attempt to design a high-performance layered cathode material for aqueous Ni-Zn batteries.

Compacting Electric Double Layer Enables Carbon Electrode with Ultrahigh Zn Ion Storage Capability.

Carbon-based cathodes for aqueous zinc ion hybrid supercapacitors (ZHSCs) typically undergo low Zn ion storage capability due to their electric double layer capacitance (EDLC) energy storage mechanism that is restricted by specific surface area and thickness of electric double layer (EDL). Here, we report a universal surface charge modulation strategy to effectively enhance the capacitance of carbon materials by decreasing the thickness of EDL. Amino groups with lone pair electrons were chosen to increase the surface charge density and enhanced the interaction between carbon electrode and Zn ions, thus effectively compacting the EDL. Consequently, amino functionalized porous carbon based ZHSCs can deliver an ultrahigh capacity of 255.2 mAh g-1 along with excellent cycling stability (95.5 % capacity retention after 50 000 cycles) in 1 M ZnCl2 electrolyte. This study demonstrates the feasibility of EDL modified carbon as Zn2+ storage cathode and great prospect for constructing high performance ZHSCs.

Hundreds-Dollar-Level Multiplex Integrated RT-qPCR Quantitative System for Field Detection.

The COVID-19 pandemic poses a threat to global health. Due to its high sensitivity, specificity, and stability, real-time fluorescence quantitative (real-time PCR) detection has become the most extensively used approach for diagnosing SARS-CoV-2 pneumonia. According to a report from the World Health Organization, emerging and underdeveloped nations lack nucleic acid detection kits and polymerase chain reaction (PCR) instruments for molecular biological detection. In addition, sending samples to a laboratory for testing may result in considerable delays between sampling and diagnosis, which is not favorable to the timely prevention and control of new crown outbreaks. Concurrently, there is an urgent demand for accurate PCR devices that do not require a laboratory setting, are more portable, and are capable of completing testing on-site. Hence, we report on HDLRT-qPCR, a new, low-cost, multiplexed real-time fluorescence detection apparatus that we have developed for on-site testing investigations of diverse diseases in developing nations. This apparatus can complete on-site testing rapidly and sensitively. The entire cost of this instrument does not exceed USD 760. In order to demonstrate the applicability of our PCR instrument, we conducted testing that revealed that we achieved gradient amplification and melting curves comparable to those of commercially available equipment. Good consistency characterized the testing outcomes. The successful detection of target genes demonstrates the reliability of our inexpensive PCR diagnostic technique. With this apparatus, there is no need to transport samples to a central laboratory; instead, we conduct testing at the sampling site. This saves time on transportation, substantially accelerates overall testing speed, and provides results within 40 min.

Unshared Pair Electrons of Zincophilic Lewis Base Enable Long-life Zn Anodes under "Three High" Conditions.

The hydrogen evolution and dendrite issues are the notorious culprits of the limited lifespan and Coulombic efficiency (CE) of Zn anodes, particularly at harsh test conditions. Herein, considering the Lewis acidic feature of Zn2+ , abundant unshared pair electrons of zincophilic Lewis bases are proposed as decent electrolyte additives to stabilize Zn anodes at "Three High" conditions (high depth of discharge, high areal capacity and high current). The unshared pair electrons can remove H2 O from Zn2+ solvated sheaths and confine the activity of H2 O by breaking its hydrogen bonding network. The combination of these factors effectively restricts H2 O-involved side reactions and enables dendrite-free Zn deposition, even at harsh conditions. The effectiveness of this strategy is fully proved by a series of Lewis base molecules. Noticeably, the Zn||Zn cell with an area of 20 cm2 , using DMF-containing electrolyte can be stably cycled over 1000 h at 60 % DOD, with a 100 % CE.

Construction of dPCR and qPCR integrated system based on commercially available low-cost hardware.

Fluorescent quantitative PCR (qPCR) and digital PCR (dPCR) are two mainstream nucleic acid quantification technologies. However, commercial dPCR and qPCR instruments have a low integration, a high price, and a large footprint. To solve these shortcomings, we introduce a compound PCR system with both qPCR and dPCR functions. All the hardware used in this compound PCR system is commercially available and low-cost, and free software was used to realize the absolute quantification of nucleic acids. The compound PCR provides two working modes. In the qPCR mode, thermal cycling is realized by controlling the reciprocating motion of the x axis. The heating rate is 1.25 °C s-1 and the cooling rate is 1.75 °C s-1. We performed amplification experiments of the PGEM-3zf (+)1 gene. The performance level was similar to commercial qPCR instruments. In the dPCR mode, the heating rate is 0.5 °C s-1 and the cooling rate is 0.6 °C s-1. We performed the UPE-Q gene amplification and used the sequential actions of the two-dimensional mechanical sliders to scan the reaction products and used the method of regional statistics and back-inference threshold to get test results. The result we got was 1208 copies per µL-1, which was similar to expectations.

Facile hydrothermal synthesis of cobaltosic sulfide nanorods for high performance supercapacitors.

With high reactivity, electrical conductivity, theoretical specific capacitance and well redox reversibility, transition metal sulfides are considered as a promising anode material for supercapacitors. Hence, we designed a simple two-step hydrothermal process to grow Co4S3 nanorod arrays in situ on flexible carbon cloth substrates. Benefited from the larger specific surface area of nanoarrays, the binder-free Co4S3 electrode demonstrates a higher specific capacity of 1.97 F cm-2 at a current density of 2 mA cm-2, while the Co3O4 electrode has a capacity of only 0.07 F cm-2 at the same current density. Surprisingly, at a high scan rate of 200 mV s-1, the synthesized Co4S3 electrode still maintains almost 100% of its initial capacitance after 5000 cycles. Moreover, when using the prepared Co4S3 and MnO2 electrode as the anode and cathode, the fabricated flexible supercapacitor obtains a high volumetric energy density of 0.87 mW h cm-3 (power density of 0.78 W cm-3) and a peak power density of 0.89 W cm-3 (energy density of 0.50 mW h cm-3). The excellent electrochemical properties imply that there is a large market for the prepared materials in flexible energy storage devices.

Intrinsic Carbon Defects Induced Reversible Antimony Chemistry for High-Energy Aqueous Alkaline Batteries.

Developing high-capacity, dendrite-free, and stable anode materials for robust aqueous alkaline batteries (AABs) is an ongoing challenge. Antimony (Sb) is predicated as an attractive anode material, but it still suffers from low capacity and poor stability caused by the obstructed kinetic behavior and uncontrollable nucleation for SbO2 - . Herein, designing a new defect-modified carbon skeleton (D-CS), a highly reversible Sb anode with ultralong cycling stability is realized at practical levels of capacity and high depth of discharge (DOD). The abundant intrinsic carbon defects can effectively form positive charge centers to weaken electrostatic repulsion between SbO2 - and electrode surface, facilitating the fast ion kinetics and provide generous controllable nucleation sites. In addition, the uniform electric field distribution of the D-CS induces manageable plating and stripping of the Sb metal, which effectively boosts its electrochemical reversibility and restrains adverse reactions. Accordingly, the Sb/D-CS electrode achieves a long cycle life of over 500 h with a capacity of 2 mAh cm-2 . Even at an ultrahigh capacity of 10 mAh cm-2 , it can still work stably up to 40 h. Furthermore, its feasibility as advanced anode in AABs is also confirmed by assembled Ni//Sb/D-CS full batteries with an ultrahigh capacity of 13.5 mAh cm-2 and a considerable stability of 4500 cycles.

Oxygen-rich interface enables reversible stibium stripping/plating chemistry in aqueous alkaline batteries.

Aqueous alkaline batteries see bright future in renewable energy storage and utilization, but their practical application is greatly challenged by the unsatisfactory performance of anode materials. Herein, we demonstrate a latent Sb stripping/plating chemistry by constructing an oxygen-rich interface on carbon substrate, thus providing a decent anode candidate. The functional interface effectively lowers the nucleation overpotential of Sb and strengthens the absorption capability of the charge carriers (SbO2- ions). These two advantageous properties inhibit the occurrence of side reactions and thus enable highly reversible Sb stripping/plating. Consequently, the Sb anode delivers theoretical-value-close specific capacity (627.1 mA h g-1), high depth of discharge (95.0%) and maintains 92.4% coulombic efficiency over 1000 cycles. A robust aqueous NiCo2O4//Sb device with high energy density and prominent durability is also demonstrated. This work provides a train of thoughts for the development of aqueous alkaline batteries based on Sb chemistry.

Dendrite-Free Zinc Deposition Induced by Multifunctional CNT Frameworks for Stable Flexible Zn-Ion Batteries.

The current boom of safe and renewable energy storage systems is driving the recent renaissance of Zn-ion batteries. However, the notorious tip-induced dendrite growth on the Zn anode restricts their further application. Herein, the first demonstration of constructing a flexible 3D carbon nanotube (CNT) framework as a Zn plating/stripping scaffold is constituted to achieve a dendrite-free robust Zn anode. Compared with the pristine deposited Zn electrode, the as-fabricated Zn/CNT anode affords lower Zn nucleation overpotential and more homogeneously distributed electric field, thus being more favorable for highly reversible Zn plating/stripping with satisfactory Coulombic efficiency rather than the formation of Zn dendrites or other byproducts. As a consequence, a highly flexible symmetric cell based on the Zn/CNT anode presents appreciably low voltage hysteresis (27 mV) and superior cycling stability (200 h) with dendrite-free morphology at 2 mA cm-2 , accompanied by a high depth of discharge (DOD) of 28%. Such distinct performance overmatches most of recently reported Zn-based anodes. Additionally, this efficient rechargeability of the Zn/CNT anode also enables a substantially stable Zn//MnO2 battery with 88.7% capacity retention after 1000 cycles and remarkable mechanical flexibility.

A Confinement Strategy for Stabilizing ZIF-Derived Bifunctional Catalysts as a Benchmark Cathode of Flexible All-Solid-State Zinc-Air Batteries.

Carbon composites with embedded metal/metal oxides represent a group of versatile electrochemical catalysts that has attracted extensive research attention. However, the beauty of this concept is marred by the severe carbon evaporation and the aggregation of metal species during their synthetic process, leading to the diminishment in active sites and catalytic durability. To address this issue, this study demonstrates the feasibility of utilizing Al2 O3 nanolayer to trap volatile carbon and nitrogen species and alleviate the aggregation of Co species during the pyrolysis of the Zn/Co-ZIFs (ZIF = zeolitic imidazolate framework). With the confinement effect of an Al2 O3 nanolayer, the derived Co3 O4 -embedded N-doped porous carbon grown on carbon cloth presents outstanding bifunctional catalytic activity with a small potential difference of 787 mV between the half-wave potential of the oxygen reduction reaction and an overpotential at 10 mA cm-2 of the oxygen evolution reaction. More impressively, an advanced flexible rechargeable zinc-air battery in all-solid-state configuration is assembled, which achieves the maximum power density of 72.4 mW cm-3 and good cycling stability. The insights produced in this work will provide guidance for the rational design of metal/carbon hybrid catalysts and low-cost renewable energy systems.

Porous MoO2 nanowires as stable and high-rate negative electrodes for electrochemical capacitors.

Free-standing porous MoO2 nanowires with extraordinary capacitive performance are developed as high-performance electrodes for electrochemical capacitors. The as-obtained MoO2 electrode exhibits a remarkable capacitance of 424.4 mF cm-2 with excellent electrochemical durability (no capacitance decay after 10 000 cycles at various scan rates).

Facile synthesis of free-standing CeO(2) nanorods for photoelectrochemical applications.

Free-standing CeO(2) nanorods with different morphology grew directly on Ti substrates via an electrochemical assembly process, and their absorption edges show a remarkable red-shift to the visible region. Moreover, photoelectrochemical cell (PEC) measurements demonstrate these CeO(2) nanorods exhibit a photovoltaic response under visible light illumination (λ≥ 390 nm).

Facile electrochemical synthesis of single crystalline CeO2 octahedrons and their optical properties.

We developed a simple electrochemical process for the large-scale fabrication of single crystalline CeO(2) octahedrons and nanospheres from DMSO aqueous solution. The octahedrons with some structural defects have a size ranging from 200 to 300 nm. Moreover, highly crystalline CeO(2) nanospheres were also obtained via this electrochemical process based on the oriented attachment mechanism. The absorption edge of octahedrons and spheres shows a red-shift, and that of the octahedrons was near the visible region.